1. Field of the Invention
The present invention generally relates to image readers, and more particularly to an image reader having photoelectric conversion line sensors.
2. Description of the Prior Art
Recently, there has been a requirement for photoelectric conversion scanners capable of reading images at high speed with precision. CCD (Charge-Coupled Device) line sensors are suitable for such high-speed, high-precision photoelectric conversion scanners.
Japanese Patent Publication No. 1-53538 discloses an image reader using CCD line sensors. An original to be optically read is divided into a plurality of read areas. A plurality of CCD line sensors, which are respectively provided for the read areas, are arranged in a main scanning direction. Use of a plurality of CCD line sensors is intended to enable reading of the images of the original at high speed and with high read density.
However, the image reader disclosed in the publication has the following disadvantages. All pixel information of the CCD line sensors are read and simply joined together so that pixel information along a line in the main scanning direction can be produced. Hence, the read operation cannot be efficiently performed. The pixel information output from the CCD line sensors contains unnecessary information, particularly, when the original has a size smaller, in the main scanning direction, than the length of the line arrangement of the CCD line sensors.